饱和储层砂岩中流体粘度引起的超声波速度频散实验研究(英文)   总被引：8，自引：3，他引：5  

何涛  邹长春  裴发根  任科英  孔繁达  史謌 《应用地球物理》2010,7(2):114-126

在实验室对5块储层砂岩进行了模拟地层压力条件下的超声波速度测试。砂岩样品采自WXS凹陷的W地层,覆盖了从低到高的孔隙度和渗透率范围。实验选用了卤水和4种不同密度油作为孔隙流体,结合温度变化,实现了对流体粘度引致的速度频散研究。对实验结果的分析表明:(1)对于高孔隙度和渗透率的样品,无论是哪种流体饱和,观察到的超声波速度测试值和零频率Gassmann预测值的差异较小(约2-3%),基本上可以用Biot模型解释;对于中等孔隙度和渗透率的样品,低粘度流体(<约3mP?S)的频散效应也可以用Biot模型得到合理解释;(2)对于低、中孔隙度和渗透率样品,当流体粘度增加时,喷射流机制起主导作用,导致严重的速度频散(可达8%)。对储层砂岩的微裂隙纵横比进行了估计并用于喷射流特征频率的计算,当高于该特征频率时,Gassmann理论的假设条件受到破坏,实验室测得的高频速度不能直接用于地震低频条件下的W地层砂岩的Gassmann流体替换研究。  相似文献   

Synthesis of Multiwalled Carbon Nanotube Modified BiOCl Microspheres with Enhanced Visible‐Light Response Photoactivity          下载免费PDF全文

Jun Di  Ming Li  Wenmin Fan  Jiexiang Xia  Hui Xu  Yilin Sun  Huaming Li 《洁净——土壤、空气、水》2016,44(7):781-787

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盐岩三轴压缩破坏与声波声发射特征试验研究     

李浩然  杨春和  赵维刚  刘博  尹雪英 《岩土力学》2016,37(9):2458-2466

利用岩石声波-声发射一体化测试系统与应力加载装置,系统地研究了三轴压缩试验中盐岩的变形破坏特征与声波声发射活动规律。结果表明：（1）三轴加载试验中,盐岩的破坏过程分为压密与弹性压缩阶段、裂纹产生与稳定增长阶段、裂纹加速增长阶段和应变硬化阶段。阶段Ⅰ中,盐岩纵横波波速略微上升,并伴随少量的声发射事件;阶段Ⅱ中,盐岩的声发射活动开始活跃,超声波波速稳定;阶段Ⅲ和阶段Ⅳ中,岩石的声发射事件数量大幅度上升,纵波波速保持稳定,横波波速呈现明显地下降趋势。（2）盐岩的声波与声发射特征与试验围压应力密切相关。围压水平越低,受载盐岩破坏过程中的波速变化率越大;围压水平越高,盐岩超声波波速变化率越小。根据对试验数据的分析,当盐岩轴向应变达到10%,围压条件为5、10、15、20 MPa时盐岩的声发射事件数量分别为16 271、8 764、3 041、906个,围压对盐岩破坏过程的声发射活动有较大的影响,显示了围压致密效应。  相似文献   

Optimization of sample pretreatment for determination of polycyclic aromatic hydrocarbons in estuarine sediments by gas chromatography     

Yan Wang  Xianguo Li  Xuewei Peng  Xuli Tang  Xiaoyan Deng 《中国海洋大学学报(英文版)》2012,11(2):159-164

This study examined levels of polycyclic aromatic hydrocarbons (PAHs) in estuarine sediments in Licun (Qingdao, China) by gas chromatography under optimized conditions for sample pretreatment via ultrasonic extraction, column chromatography, and thin layer chromatography. Methanol and dichloromethane (DCM)/methanol (2:1, v/v) were used in ultrasonic extraction, and DCM was used as eluate for column chromatography. The developing system consisted of n-hexane and DCM at a ratio of 9:1 (v/v), with DCM as the extraction solvent for PAHs-containing silica gel scraped off the plate. When the spiking level is 100 ng, total recoveries of spiked matrices for four target PAHs (phenanthrene, anthracene, pyrene and chrysene) were 83.7%, 76.4%, 85.8%, and 88.7%, respectively, with relative standard deviation (RSD) between 5.0% and 6.5% (n = 4). When the spiking level is 1000 ng, associated total recoveries were 78.6%, 72.7%, 82.7% and 85.3%, respectively, with RSD between 4.4% and 5.3% (n = 4). The opti-mized method was advantageous for determination of PAHs in complex matrix due to its effective sample purification.  相似文献   

Variable and conflicting shear stress estimates inside a boundary layer with sediment transport          下载免费PDF全文

Zoë S. Lee  Andreas C. W. Baas 《地球表面变化过程与地形》2016,41(4):435-445

This paper presents a comparison between two methods for estimating shear stress in an atmospheric internal boundary layer over a beach surface under optimum conditions, using wind velocities measured synchronously at 13 heights over a 1.7 m vertical array using ultrasonic anemometry. The Reynolds decomposition technique determines at‐a‐point shear stresses at each measurement height, while the Law‐of‐the‐Wall yields a single boundary layer estimate based on fitting a logarithmic velocity profile through the array data. Analysis reveals significant inconsistencies between estimates derived from the two methods, on both a whole‐event basis and as time‐series. Despite a near‐perfect fit of the Law‐of‐the‐Wall, the point estimates of Reynolds shear stress vary greatly between heights, calling into question the assumed presence of a constant stress layer. A comparison with simultaneously measured sediment transport finds no relationship between transport activity and the discrepancies in shear stress estimates. Results do show, however, that Reynolds shear stress measured nearer the bed exhibits slightly better correlation with sand transport rate. The findings serve as a major cautionary message to the interpretation and application of single‐height measurements of Reynolds shear stress and their equivalence to Law‐of‐the‐Wall derived estimates, and these concerns apply widely to boundary layer flows in general. © 2015 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.  相似文献   

The Effects of Terrain Slope and Orientation on Different Weather Processes in China under Different Model Resolutions          下载免费PDF全文

HUANG Danqing  QIAN Yongfu 《Acta Meteorologica Sinica》2009,23(5):617-628

Currently, short wave radiation at the ground surface (GSW) is calculated under the assumption of a horizontal surface. This method of estimating the GSW may lead to considerable errors when the model resolution becomes higher and the model terrain becomes steeper. In this paper, to improve the short wave solar radiation simulations, a terrain slope and orientation parameterization has been implemented into the non-hydrostatic mesoscale model GRAPES (Global/Regional Assimilation and Prediction System). The effects of the terrain slope and orientation on different short range weather processes in China under different model resolutions are simulated and discussed. In the simulations, topography height is taken from NCEP(National Centers for Environmental Prediction) with a resolution of 1 km, and the slope and orientation of terrain are calculated using different staggering schemes and under di erent weather conditions. The results show that when the model resolution is low (30 and 60 km) and the slope of terrain is not large, the influence of the slope and orientation of terrain on the GSW is not evident; otherwise, however, it is not negligible. Under high model resolutions (3 and 6 km), the increase (decrease) of simulated precipitation corresponds to the decrease (increase) of the GSW induced by the slope effect, and the variations of precipitation are usually ranged between －5 and 5 mm. Under the high resolution, the surface temperature and heat fluxes are strongly correlated to each other and the high correlation exists mostly in the complex terrain regions. The changes of the GSW, precipitation, surface temperature, and heat fluxes induced by the e ects of the terrain slope and orientation are more obvious in mountainous regions, due to the alternations in the atmospheric circulation. It is found as well that under the weather condition of less cloud and less precipitation, the effects of the terrain slope and orientation can be more realistically seen. Therefore, the terrain slope and orientation can usually be neglected in numerical models when the horizontal model resolution is low and the slopes are moderate, but should be taken into account when the model resolution becomes high and the terrain is steep and undulating.  相似文献   

The Effects of Terrain Slope and Orientation on Different Weather Processes in China under Different Model Resolutions          下载免费PDF全文

黄丹青  钱永甫 《Acta Meteorologica Sinica》2009,23(5):617-628

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超声风速温度仪的误差分析与检定方法研究   总被引：1，自引：0，他引：1  

李增志  黄峰  朱福萌  王金刚 《气象研究与应用》2009,30(1):58-59,62

根据超声风速温度仪的原理,分析了其测量误差的主要来源,进而总结出两个主要误差项.针对这两个主要误差项提出了一种快速的误差检定方法,理论上只需两次测量即可完成对风速温度的误差检定.同时分析了不同温度条件下相对湿度对超声风速温度仪测温的影响,并给出了相关结论.  相似文献   

Advances in Microgeophysics for Engineering and Cultural Heritage     

P L Cosentino  P Capizzi  G Fiandaca  R Martorana  P Messina 《中国地质大学学报(英文版)》2009,20(3)

A large number of unconventional investigations have been implemented, tested, and validated in the field of microgeophysics, with the aim being to solve specific diagnostic and/or monitoring problems regarding civli engineering and cultural beritage studies. The investigations were carried out using different tomographic 2D and 3D approaches as well as different energy sources, namely sonic, ultrasonic and electromagnetic (radar) waves, electric potential fields, and infrared thermography. Many efforts have been made to modify instruments and procedures in order to improve the resolution of the surveys as well as to greatly reduce the time of the measurements without any loss of information. The main new methodologies here discussed arc the sonic imprint, the global tomographic traveltime, the electrical resistivity tomography, and the control of external films (patinas) grown on stone monuments. The results seem to be very promising and suggest that it is the moment to dedicate time and effort to this new branch of geophysics, so that these methodologies can be used even more to diagnose, monitor, and safeguard not only engineering buildings and large structures but also ancient monuments and cultural artifacts, like pottery, statues, etc..  相似文献   

超声波在粘弹性混凝土介质中传播机理研究     

鲁光银  张志勇  朱自强  付渝渝 《物探化探计算技术》2019,(3):299-307

混凝土是一种含有骨料、水泥浆、钢筋、波纹管包裹的预应力孔道及空洞、孔隙的多相非均匀复合材料,作为一种粘弹性介质,超声在混凝土中传播机理比较复杂,常规的弹性声波方程不能确切地模拟超声传播方式。这里从粘弹性介质材料性质出发,推导了基于Kelvin粘弹性介质模型的高阶有限差分方程,通过建立几种粘弹性混凝土介质数值模型,模拟了超声波在混凝土中的传播过程,分析了含空洞、裂隙等不同缺陷的混凝土介质中超声波的波形特性,讨论了缺陷部位波形的变化规律,探讨了空洞、裂隙等不同缺陷对超声传播机理的影响以及能量分布的差异,为准确判断识别混凝土内部不同结构的缺陷提供科学借鉴。  相似文献